Manual silk screen printers are designed to print only a specific number of colors, and dimensionally unstable material, such as T-shirts, cannot be moved to a second printer if it is desired to print additional colors, because the shirt will move while it is being transferred and the subsequent colors will not be in registry with the previous colors. Thus, it is necessary for a silk screen print shop to have a printer that is capable of printing the maximum number of colors that will ever be required, even though most of the time a lesser number of colors will be printed. This is not cost effective because the greater the color capability of a printer, the greater its cost. For example, if a print shop occasionally printed shirts with eight colors but only required four colors on most jobs, it would have to buy an eight-color printer. However, an eight-color printer costs substantially more than a four-color printer, and the additional money would be better spent in purchasing two four-color printers which would double the production capability of the shop most of the time.
In addition, it often is desirable to perform non-silk screen processes between silk screen colors, and most non-silk screen processes require removing the material from the printer. However, because of their dimensional instability this cannot be done with shirts without loss of registry. Thus, it is not possible to perform a non-silk screen process between silk screen colors on a shirt.
An example of a non-silk screen process that needs to be performed between the printing of silk screen colors is the application of a foil coating. When a foil coating is applied on a shirt it does not adhere to the shirt itself but only to ink on the shirt. Thus, an undercoat is first applied to the shirt by silk screen that covers the area that is to have foil. The foil is applied onto this undercoat and then the colors are applied by silk screen. In addition, it often is desirable to apply airbrush or hand-painted art to a shirt between colors to obtain an effect that would not be available if the art was applied before or after all of the colors.
The subject invention overcomes the foregoing limitations of prior art silk screening of shirts by making the platen removable from the rest of the apparatus with the shirt affixed to it to perform the non-silk screen processes and still be replaceable on the same or another printer without disrupting the shirt, thereby allowing registry to be maintained. This is accomplished in a preferred embodiment of the invention by dividing the platen into a fixed bottom piece that is attached to the rest of the apparatus and a removable top piece that the shirt is adhesively attached to. The top and bottom pieces are indexed relative to one another so that registry is maintained when the top piece is removed and reinstalled on the bottom piece. In addition, the indexing secures the top piece immovable relative to the bottom piece when it is installed.
In a preferred embodiment this is accomplished by placing a plurality of projecting pins on the bottom piece and placing aligned holes in the top piece that snugly receive the pins. The pins are positioned uniformly on each bottom piece on every apparatus and the holes are positioned uniformly on every top piece. Thus, registry is maintained not only when a top piece is removed and reinstalled on the same bottom piece, but when it is installed on another bottom piece on the same apparatus or on a bottom piece on another apparatus. As a result, a top piece with a shirt attached can be removed from one apparatus to another in order to print more colors than would be possible with either apparatus alone, or a top piece can be removed from its bottom piece with the shirt attached to perform a non-silk screen process on the shirt and then reinstalled on the same bottom piece to finish the silk screen printing. In either case registry is maintained throughout the process.
Accordingly, it is a principal object of the subject invention to provide a multi-color silk screen printer for shirts in which the shirts can be removed from one printer and placed on another printer without loss of registry in order to print more colors than would be possible with either printer alone.
It is a further object of the subject invention to provide a silk screen printer having a platen which can be removed from the remainder of the apparatus with a shirt attached and then placed back on the apparatus without loss of registry between the shirt and the silk screens being carried by the apparatus.
It is a further object of the subject invention to provide a silk screen printer in which the shirts can be removed from the printer for performing non-silk screen processes and then placed back on the printer without loss of registry.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.